Mask for TextField

I couldn't find a plugin to mask a TextField the way I need it. The only one that did what I was looking for was this one http://digitalbush.com/projects/masked-input-plugin/ but it was for jQuery. So I decided to "port it" over to ExtJS.
First I tried to make it a plugin but I decided to overwrite the TextField class so subclasses will inherit it too.

One thing to notice is that if your component is already initialized you need to call initMask() to initialize the mask. Also make sure you set it up with enableKeyEvents so keydown and keypress get register. I'm working on a way to allow the mask to be changed after the initialization and also remove the mask all-together.